Genetic deletion of microsomal prostaglandin E synthase-1 suppresses mouse mammary tumor growth and angiogenesis

Novel 1,2,4-triazoles derived from Ibuprofen: synthesis and in vitro evaluation of their mPGES-1 inhibitory and antiproliferative activity

Some novel triazole-bearing ketone and oxime derivatives were synthesized from Ibuprofen. In vitro cytotoxic activities of all synthesized molecules against five cancer lines (human breast cancer MCF-7, human lung cancer A549, human prostate cancer PC-3, human cervix cancer HeLa, and human chronic myelogenous leukemia K562 cell lines) were evaluated by MTT assay. In addition, mouse embryonic fibroblast cells (NIH/3T3) were also evaluated to determine the selectivity. Compounds 18, 36, and 45 were found to be the most cytotoxic, and their IC50 values were in the range of 17.46-68.76 µM, against the tested cancer cells. According to the results, compounds 7 and 13 demonstrated good anti-inflammatory activity against the microsomal enzyme prostaglandin E2 synthase-1 (mPGES-1) enzyme at IC50 values of 13.6 and 4.95 µM. The low cytotoxicity and non-mutagenity of these compounds were found interesting. Also, these compounds significantly prevented tube formation in angiogenesis studies. In conclusion, the anti-inflammatory and angiogenesis inhibitory activities of these compounds without toxicity suggested that they may be promising agents in anti-inflammatory treatment and they may be supportive agents for the cancer treatment.

Prostaglandin E2 and Cancer: Insight into Tumor Progression and Immunity

The involvement of inflammation in cancer progression has been the subject of research for many years. Inflammatory milieu and immune response are associated with cancer progression and recurrence. In different types of tumors, growth and metastatic phenotype characterized by the epithelial mesenchymal transition (EMT) process, stemness, and angiogenesis, are increasingly associated with intrinsic or extrinsic inflammation. Among the inflammatory mediators, prostaglandin E2 (PGE2) supports epithelial tumor aggressiveness by several mechanisms, including growth promotion, escape from apoptosis, transactivation of tyrosine kinase growth factor receptors, and induction of angiogenesis. Moreover, PGE2 is an important player in the tumor microenvironment, where it suppresses antitumor immunity and regulates tumor immune evasion, leading to increased tumoral progression. In this review, we describe the current knowledge on the pro-tumoral activity of PGE2 focusing on its role in cancer progression and in the regulation of the tumor microenvironment.

Mechanistic definition of the cardiovascular mPGES-1/COX-2/ADMA axis

AIMS

Cardiovascular side effects caused by non-steroidal anti-inflammatory drugs (NSAIDs), which all inhibit cyclooxygenase (COX)-2, have prevented development of new drugs that target prostaglandins to treat inflammation and cancer. Microsomal prostaglandin E synthase-1 (mPGES-1) inhibitors have efficacy in the NSAID arena but their cardiovascular safety is not known. Our previous work identified asymmetric dimethylarginine (ADMA), an inhibitor of endothelial nitric oxide synthase, as a potential biomarker of cardiovascular toxicity associated with blockade of COX-2. Here, we have used pharmacological tools and genetically modified mice to delineate mPGES-1 and COX-2 in the regulation of ADMA.

METHODS AND RESULTS

Inhibition of COX-2 but not mPGES-1 deletion resulted in increased plasma ADMA levels. mPGES-1 deletion but not COX-2 inhibition resulted in increased plasma prostacyclin levels. These differences were explained by distinct compartmentalization of COX-2 and mPGES-1 in the kidney. Data from prostanoid synthase/receptor knockout mice showed that the COX-2/ADMA axis is controlled by prostacyclin receptors (IP and PPARβ/δ) and the inhibitory PGE2 receptor EP4, but not other PGE2 receptors.

CONCLUSION

These data demonstrate that inhibition of mPGES-1 spares the renal COX-2/ADMA pathway and define mechanistically how COX-2 regulates ADMA.

Prostaglandin E2 as a therapeutic target in bladder cancer: From basic science to clinical trials

Bladder cancer (BCa) is a common solid tumor marked by high rates of recurrence, especially in non-muscle invasive disease. Prostaglandin E₂ (PGE₂) is a ubiquitously present lipid mediator responsible for numerous physiological actions. Inhibition of cyclooxygenase (COX) enzymes by the non-steroidal anti-inflammatory (NSAID) class of drugs results in reduced PGE₂ levels. NSAID usage has been associated with reductions in cancers such as BCa. Clinical trials using NSAIDs to prevent recurrence have had mixed results, but largely converge on issues with cardiotoxicity. The purpose of this review is to understand the basic science behind how and why inhibitors of PGE₂ may be effective against BCa, and to explore alternate therapeutic modalities for addressing the role of PGE₂ without the associated cardiotoxicity. We will address the role of PGE₂ in a diverse array of cancer-related functions including stemness, immunosuppression, proliferation, cellular signaling and more.

Prostaglandin E2 receptor EP2 mediates the effect of cyclooxygenase 2 on secondary parathyroid hyperplasia in end-stage renal disease

BACKGROUND

Secondary hyperparathyroidism (SHPT) in patients with end-stage renal disease (ESRD) is characterized by hyperplasia of the parathyroid glands (PTGs), while the underlying mechanism is not completely understood. Previously we demonstrated a relationship between cyclooxygenase 2 (COX2) overexpression and parathyroid hyperplasia and here we investigate the role of COX2 downstream metabolic product prostaglandin E2 (PGE2) and its receptor EP2 in the pathogenesis of SHPT.

METHODS

PTGs isolated from ESRD patients with advanced SHPT were used to test the expression of COX2-microsomal prostaglandin E synthase-1 (mPGES-1)-EP2 pathway. A diffuse proliferative section of the PTGs was used for tissue culture and treated with high phosphate (HPi) medium, COX2-PGE2-EP2 pathway inhibitors or agonists. EP2 short hairpin RNA (shRNA) lentivirus was locally applied to treat an SHPT rat model.

RESULTS

In PTGs isolated from ESRD patients, enhanced immunoactivities of COX2, mPGES-1 and EP2 were observed. In primary cultured PTG tissues, HPi induced intact parathyroid hormone (iPTH) secretion, proliferating cell nuclear antigen (PCNA) expression and COX2 activity, while COX2 and EP2 inhibitors attenuated hyperparathyroidism promoted by HPi. Furthermore, PGE2 or EP2 agonist (butaprost) directly stimulated hyperparathyroidism, whereas EP2 receptor antagonist or cyclic adenosine monophosphate inhibitor attenuated the hyperparathyroidism promoted by PGE2 or butaprost. EP2 shRNA treatment significantly reduced excessive expressions of EP2 and PCNA in the PTGs of nephrectomy rats fed an HPi diet, diminished the size of PTGs and downregulated serum iPTH levels.

CONCLUSIONS

The COX2 downstream PGE2 and its receptor EP2 may play an important role in HPi-induced parathyroid hyperplasia and may serve as a potential therapeutic target for SHPT in ESRD.

Biological characterization of new inhibitors of microsomal PGE synthase-1 in preclinical models of inflammation and vascular tone

BACKGROUND AND PURPOSE

Microsomal PGE synthase-1 (mPGES-1), the inducible synthase that catalyses the terminal step in PGE₂ biosynthesis, is of high interest as therapeutic target to treat inflammation. Inhibition of mPGES-1 is suggested to be safer than traditional NSAIDs, and recent data demonstrate anti-constrictive effects on vascular tone, indicating new therapeutic opportunities. However, there is a lack of potent mPGES-1 inhibitors lacking interspecies differences for conducting in vivo studies in relevant preclinical disease models.

EXPERIMENTAL APPROACH

Potency was determined based on the reduction of PGE₂ formation in recombinant enzyme assays, cellular assay, human whole blood assay, and air pouch mouse model. Anti-inflammatory properties were assessed by acute paw swelling in a paw oedema rat model. Effect on vascular tone was determined with human ex vivo wire myography.

KEY RESULTS

We report five new mPGES-1 inhibitors (named 934, 117, 118, 322, and 323) that selectively inhibit recombinant human and rat mPGES-1 with IC₅₀ values of 10-29 and 67-250 nM respectively. The compounds inhibited PGE₂ production in a cellular assay (IC₅₀ values 0.15-0.82 μM) and in a human whole blood assay (IC₅₀ values 3.3-8.7 μM). Moreover, the compounds blocked PGE₂ formation in an air pouch mouse model and reduced acute paw swelling in a paw oedema rat model. Human ex vivo wire myography analysis showed reduced adrenergic vasoconstriction after incubation with the compounds.

CONCLUSION AND IMPLICATIONS

These mPGES-1 inhibitors can be used as refined tools in further investigations of the role of mPGES-1 in inflammation and microvascular disease.

A review on mPGES-1 inhibitors: From preclinical studies to clinical applications

Prostaglandin E₂ (PGE₂) is a lipid mediator of inflammation and cancer progression. It is mainly formed via metabolism of arachidonic acid by cyclooxygenases (COX) and the terminal enzyme microsomal prostaglandin E synthase-1 (mPGES-1). Widely used non-steroidal anti-inflammatory drugs (NSAIDs) inhibit COX activity, resulting in decreased PGE₂ production and symptomatic relief. However, NSAIDs block the production of many other lipid mediators that have important physiological and resolving actions, and these drugs cause gastrointestinal bleeding and/or increase the risk for severe cardiovascular events. Selective inhibition of downstream mPGES-1 for reduction in only PGE₂ biosynthesis is suggested as a safer therapeutic strategy. This review covers the recent advances in characterization of new mPGES-1 inhibitors in preclinical models and their future clinical applications.

Drugging cancer metabolism: Expectations vs. reality

As compared to their normal counterparts, neoplastic cells exhibit a variety of metabolic changes that reflect not only genetic and epigenetic defects underlying malignant transformation, but also the nutritional and immunobiological conditions of the tumor microenvironment. Such alterations, including the so-called Warburg effect (an increase in glucose uptake largely feeding anabolic and antioxidant metabolism), have attracted considerable attention as potential targets for the development of novel anticancer therapeutics. However, very few drugs specifically conceived to target bioenergetic cancer metabolism are currently approved by regulatory agencies for use in humans. This reflects the elevated degree of heterogeneity and redundancy in the metabolic circuitries exploited by neoplastic cells from different tumors (even of the same type), as well as the resemblance of such metabolic pathways to those employed by highly proliferating normal cells. Here, we summarize the major metabolic alterations that accompany oncogenesis, the potential of targeting bioenergetic metabolism for cancer therapy, and the obstacles that still prevent the clinical translation of such a promising therapeutic paradigm.

Inhibition of mPGES-1 or COX-2 Results in Different Proteomic and Lipidomic Profiles in A549 Lung Cancer Cells

Pharmacological inhibition of microsomal prostaglandin E synthase (mPGES)-1 for selective reduction in prostaglandin E₂ (PGE₂) biosynthesis is protective in experimental models of cancer and inflammation. Targeting mPGES-1 is envisioned as a safer alternative to traditional non-steroidal anti-inflammatory drugs (NSAIDs). Herein, we compared the effects of mPGES-1 inhibitor Compound III (CIII) with the cyclooxygenase (COX)-2 inhibitor NS-398 on protein and lipid profiles in interleukin (IL)-1β-induced A549 lung cancer cells using mass spectrometry. Inhibition of mPGES-1 decreased PGE₂ production and increased PGF_2α and thromboxane B₂ (TXB₂) formation, while inhibition of COX-2 decreased the production of all three prostanoids. Our proteomics results revealed that CIII downregulated multiple canonical pathways including eIF2, eIF4/P70S6K, and mTOR signaling, compared to NS-398 that activated these pathways. Moreover, pathway analysis predicted that CIII increased cell death of cancer cells (Z = 3.8, p = 5.1E-41) while NS-398 decreased the same function (Z = -5.0, p = 6.5E-35). In our lipidomics analyses, we found alterations in nine phospholipids between the two inhibitors, with a stronger alteration in the lysophospholipid (LPC) profile with NS-398 compared to CIII. Inhibition of mPGES-1 increased the concentration of sphinganine and dihydroceramide (C_16:0DhCer), while inhibition of COX-2 caused a general decrease in most ceramides, again suggesting different effects on cell death between the two inhibitors. We showed that CIII decreased proliferation and potentiated the cytotoxic effect of the cytostatic drugs cisplatin, etoposide, and vincristine when investigated in a live cell imaging system. Our results demonstrate differences in protein and lipid profiles after inhibition of mPGES-1 or COX-2 with important implications on the therapeutic potential of mPGES-1 inhibitors as adjuvant treatment in cancer. We encourage further investigations to illuminate the clinical benefit of mPGES-1 inhibitors in cancer.

Stabilization of PTGES by deubiquitinase USP9X promotes metastatic features of lung cancer via PGE2 signaling

Early metastasis and local recurrence are the major causes of mortality and poor prognosis of non-small cell lung cancer (NSCLC). However, the underlying mechanisms of these processes are poorly understood. In this study, we aimed to investigate the roles of the PTGES/PGE2 pathway in lung cancer progression. We found that prostaglandin E synthase (PTGES), a key enzyme for PGE2 synthesis in the arachidonic acid pathway, was highly dysregulated in NSCLC. Dysregulated PTGES was essential for the promotion of tumor migration and metastasis of NSCLC cells. Knockdown of PTGES in lung cancer cells resulted in suppressed cell migration, which was reversed by exogenous PGE2. Consistent with this, PTGES knockdown also reduced the expression of CSC markers, tumor sphere formation, colony forming activity, tumorigenicity, and lung metastasis in vivo. Dysregulated PTGES is mainly attributed to protein stabilization by USP9X, a deubiquitination enzyme. USP9X physically interacted with PTGES and prevented it from proteasome-directed degradation via deubiquitination. Consistent with this, USP9X expression was highly correlated with PTGES expression in NSCLC tumor tissues. Taken together, our results show that the upregulated USP9X-PTGES-PGE2 axis contributes significantly to the metastatic features of NSCLC.

Beyond a chemopreventive reagent, aspirin is a master regulator of the hallmarks of cancer

PURPOSE

Aspirin, one of the most commonly used nonsteroidal anti-inflammatory drugs (NAIDS), not only shows cancer chemoprevention effects but also improves cancer therapeutic effects when combined with other therapies. Studies that focus on aspirin regulation of the hallmarks of cancer and the associated molecular mechanisms facilitate a more thorough understanding of aspirin in mediating chemoprevention and may supply additional information for the development of novel cancer therapeutic agents.

METHODS

The relevant literatures from PubMed have been reviewed in this article.

RESULTS

Current studies have revealed that aspirin regulates almost all the hallmarks of cancer. Within tumor tissue, aspirin suppresses the bioactivities of cancer cells themselves and deteriorates the tumor microenvironment that supports cancer progression. In addition to tumor tissues, blocking of platelet activation also contributes to the ability of aspirin to inhibit cancer progression. In terms of the molecular mechanism, aspirin targets oncogenes and cancer-related signaling pathways and activates certain tumor suppressors.

CONCLUSION

Beyond a chemopreventive agent, aspirin is a master regulator of the hallmarks of cancer.

Prostaglandin terminal synthases as novel therapeutic targets

Non-steroidal anti-inflammatory drugs (NSAIDs) exert their anti-inflammatory and anti-tumor effects by reducing prostaglandin (PG) production via the inhibition of cyclooxygenase (COX). However, the gastrointestinal, renal and cardiovascular side effects associated with the pharmacological inhibition of the COX enzymes have focused renewed attention onto other potential targets for NSAIDs. PGH₂, a COX metabolite, is converted to each PG species by species-specific PG terminal synthases. Because of their potential for more selective modulation of PG production, PG terminal synthases are now being investigated as a novel target for NSAIDs. In this review, I summarize the current understanding of PG terminal synthases, with a focus on microsomal PGE synthase-1 (mPGES-1) and PGI synthase (PGIS). mPGES-1 and PGIS cooperatively exacerbate inflammatory reactions but have opposing effects on carcinogenesis. mPGES-1 and PGIS are expected to be attractive alternatives to COX as therapeutic targets for several diseases, including inflammatory diseases and cancer.

MPGES-1-derived PGE2 suppresses CD80 expression on tumor-associated phagocytes to inhibit anti-tumor immune responses in breast cancer

Prostaglandin E₂ (PGE₂) favors multiple aspects of tumor development and immune evasion. Therefore, microsomal prostaglandin E synthase (mPGES-1/-2), is a potential target for cancer therapy. We explored whether inhibiting mPGES-1 in human and mouse models of breast cancer affects tumor-associated immunity. A new model of breast tumor spheroid killing by human PBMCs was developed. In this model, tumor killing required CD80 expression by tumor-associated phagocytes to trigger cytotoxic T cell activation. Pharmacological mPGES-1 inhibition increased CD80 expression, whereas addition of PGE₂, a prostaglandin E2 receptor 2 (EP2) agonist, or activation of signaling downstream of EP2 reduced CD80 expression. Genetic ablation of mPGES-1 resulted in markedly reduced tumor growth in PyMT mice. Macrophages of mPGES-1^−/− PyMT mice indeed expressed elevated levels of CD80 compared to their wildtype counterparts. CD80 expression in tumor-spheroid infiltrating mPGES-1^−/− macrophages translated into antigen-specific cytotoxic T cell activation. In conclusion, mPGES-1 inhibition elevates CD80 expression by tumor-associated phagocytes to restrict tumor growth. We propose that mPGES-1 inhibition in combination with immune cell activation might be part of a therapeutic strategy to overcome the immunosuppressive tumor microenvironment.

Repurposing Drugs in Oncology (ReDO)-diclofenac as an anti-cancer agent

Diclofenac (DCF) is a well-known and widely used non-steroidal anti-inflammatory drug (NSAID), with a range of actions which are of interest in an oncological context. While there has long been an interest in the use of NSAIDs in chemoprevention, there is now emerging evidence that such drugs may have activity in a treatment setting. DCF, which is a potent inhibitor of COX-2 and prostaglandin E2 synthesis, displays a range of effects on the immune system, the angiogenic cascade, chemo- and radio-sensitivity and tumour metabolism. Both pre-clinical and clinical evidence of these effects, in multiple cancer types, is assessed and summarised and relevant mechanisms of action outlined. Based on this evidence the case is made for further clinical investigation of the anticancer effects of DCF, particularly in combination with other agents - with a range of possible multi-drug and multi-modality combinations outlined in the supplementary materials accompanying the main paper.

Expression, regulation and function of Egr1 during implantation and decidualization in mice

Abstract Early growth response gene 1 (Egr1), a zinc finger transcriptional factor, plays an important role in regulating cell proliferation, differentiation and angiogenesis. Current data have shown that Egr1 is involved in follicular development, ovulation, luteinization and placental angiogenesis. However, the expression, regulation and function of Egr1 in mouse uterus during embryo implantation and decidualization are poorly understood. Here we showed that Egr1 was strongly expressed in the subluminal stroma surrounding the implanting blastocyst on day 5 of pregnancy. Injection of Egr1 siRNA into the mouse uterine horn could obviously reduce the number of implanted embryos and affect the uterine vascular permeability. Further study found that Egr1 played a role through influencing the expression of cyclooxygenase-2 (Cox-2), microsomal prostaglandin E synthase 1 (mPGES-1), vascular endothelial growth factor (Vegf), transformation related protein 53 (Trp53) and matrix metallopeptidase 9 (Mmp9) genes in the process of mouse embryo implantation. Growth hormone (GH) and insulin-like growth factor 1 (IGF-1) might direct the expression of Egr1 in the uterine stromal cells. Under in vivo and in vitro artificial decidualization, Egr1 expression was significantly decreased. Overexpression of Egr1 downregulated the expression of decidual marker decidual/trophoblast PRL-related protein (Dtprp) in the uterine stromal cells, while inhibition of Egr1 upregulated the expression of Dtprp under in vitro decidualization. Estrogen and progesterone could regulate the expression of Egr1 in the ovariectomized mouse uterus and uterine stromal cells. These results suggest that Egr1 may be essential for embryo implantation and decidualization.

Diacetyloxyl derivatization of the fibroblast growth factor inhibitor dobesilate enhances its anti-inflammatory, anti-angiogenic and anti-tumoral activities

BACKGROUND

Dobesilate (2,5-dihydroxyphenyl sulfonate, DHPS) was recently identified as the most potent member of a family of fibroblast growth factor (FGF) inhibitors headed by gentisic acid, one of the main catabolites of aspirin. Although FGFs were first described as inducers of angiogenesis, they were soon recognized as broad spectrum mitogens. Furthermore, in the last decade these proteins have been shown to participate directly in the onset of inflammation, and their potential angiogenic activity often contributes to the inflammatory process in vivo. The aim of this work was to evaluate the anti-inflammatory, anti-angiogenic and anti-tumoral activities of the derivative of DHPS obtained by acetoxylation of its two hydroxyl groups (2,5-diacetoxyphenyl sulfonate; DAPS).

METHODS

Anti-inflammatory, anti-angiogenic and anti-tumoral activities of DHPS and DAPS were compared using in vivo assays of dermatitis, angiogenesis and tumorigenesis. The effects of both compounds on myeloperoxidase (MPO) and cyclooxygenase (COX) activities, cytokine production and FGF-induced fibroblast proliferation were also determined.

RESULTS

Topical DAPS is more effective than DHPS in preventing inflammatory signs (increased vascular permeability, edema, leukocyte infiltration, MPO activation) caused by contact dermatitis induction in rat ears. DAPS, but not DHPS, effectively inhibits COX-1 and COX-2 activities. DAPS also reduces the increase in serum cytokine concentration induced by lipopolysaccharide in rats. Furthermore, DAPS displays higher in vivo efficacy than DHPS in inhibiting FGF-induced angiogenesis and heterotopic glioma progression, with demonstrated oral efficacy to combat both processes.

CONCLUSIONS

By inhibiting both FGF-signaling and COX-mediated prostaglandin synthesis, DAPS efficiently breaks the vicious circle created by the reciprocal induction of FGF and prostaglandins, which probably sustains undesirable inflammation in many circumstances. Our findings define the enhancement of anti-inflammatory, anti-angiogenic and anti-tumoral activities by diacetyloxyl derivatization of the FGF inhibitor, dobesilate.

Non-cell autonomous effects of targeting inducible PGE2 synthesis during inflammation-associated colon carcinogenesis

Microsomal PGE2 synthase-1 (mPGES-1), the terminal enzyme in the formation of inducible PGE2, represents a potential target for cancer chemoprevention. We have previously shown that genetic abrogation of mPGES-1 significantly suppresses tumorigenesis in two preclinical models of intestinal cancer. In this study, we examined the role of mPGES-1 during colon tumorigenesis in the presence of dextran sulfate sodium (DSS)-induced inflammatory microenvironment. Using Apc (Δ14/+) in which the mPGES-1 gene is either wild-type (D14:WT) or deleted (D14:KO), we report that mPGES-1 deficiency enhances sensitivity to acute mucosal injury. As a result of the increased epithelial damage, protection against adenoma formation is unexpectedly compromised in the D14:KO mice. Examining the DSS-induced acute injury, cryptal structures are formed within inflamed areas of colonic mucosa of both genotypes that display the hallmarks of early neoplasia. When acute epithelial injury is balanced by titration of DSS exposures, however, these small cryptal lesions progress rapidly to adenomas in the D14:WT mice. Given that mPGES-1 is highly expressed within the intestinal stroma under the inflammatory conditions of DSS-induced ulceration, we propose a complex and dual role for inducible PGE2 synthesis within the colonic mucosa. Our data suggest that inducible PGE2 is critical for the maintenance of an intact colonic epithelial barrier, while promoting epithelial regeneration. This function is exploited during neoplastic transformation in Apc (Δ14/+) mice as PGE2 contributes to the growth and expansion of the early initiated cryptal structures. Taken together, inducible PGE2 plays a complex role in inflammation-associated cancers that requires further analysis. Inducible PGE2 production by mPGES-1 is critical for the colonic mucosal homeostasis. This function is exploited in the presence of the neoplastic transformation in Apc (Δ14/+) mice as PGE2 contributes to the growth and expansion of the early cryptal structures.

Factors predicting outcome after salvage treatment for stage IV oral squamous cell carcinoma: Evidence of the potential importance of the cyclooxygenase-2-prostaglandin E2 pathway

BACKGROUND

We determined the clinicopathological factors that predicted outcome after salvage treatment for stage IV oral squamous cell carcinoma (OSCC). Additionally, the prognostic significance of the cyclooxygenase-2 (COX-2)/microsomal prostaglandin-E synthase-1 (mPGES-1) pathway was evaluated.

METHODS

Thirty-one patients who underwent salvage surgery were included. COX-2 and mPGES-1 levels were quantified by real time polymerase chain reaction (PCR).

RESULTS

The 2-year disease-free and overall survival rates were 46% and 53%, respectively. Adequacy of initial treatment, tobacco smoking, and the presence of pathological risk factors were predictive of mortality. In patients who had not received chemotherapy before salvage surgery, high levels of intratumoral COX-2 and mPGES-1 were associated with poor prognosis. By contrast, high intratumoral COX-2 and mPGES-1 after chemotherapy were associated with improved outcomes.

CONCLUSION

Clinicopathological factors may inform treatment decisions in patients with stage IV OSCC. Expression patterns of COX-2 and mPGES-1 correlated with outcome and warrant further investigation. © 2014 Wiley Periodicals, Inc. Head Neck 37: 1142-1149, 2015.

Prostaglandin receptor EP2 in the crosshairs of anti-inflammation, anti-cancer, and neuroprotection

Modulation of a specific prostanoid synthase or receptor provides therapeutic alternatives to nonsteroidal anti-inflammatory drugs (NSAIDs) for treating pathological conditions governed by cyclooxygenase-2 (COX-2 or PTGS2). Among the COX-2 downstream signaling pathways, the prostaglandin E2 (PGE2) receptor EP2 subtype (PTGER2) is emerging as a crucial mediator of many physiological and pathological events. Genetic ablation strategies and recent advances in chemical biology provide tools for a better understanding of EP2 signaling. In the brain, the EP2 receptor modulates some beneficial effects, including neuroprotection, in acute models of excitotoxicity, neuroplasticity, and spatial learning via cAMP-PKA signaling. Conversely, EP2 activation accentuates chronic inflammation mainly through the cAMP-Epac pathway, likely contributing to delayed neurotoxicity. EP2 receptor activation also engages β-arrestin in a G-protein-independent pathway that promotes tumor cell growth and migration. Understanding the conditions under which multiple EP2 signaling pathways are engaged might suggest novel therapeutic strategies to target this key inflammatory prostaglandin receptor.